How to Calculate Percentages
Percentages are used everywhere — from discounts and taxes to grades and statistics. Understanding percentage formulas is an essential math skill.
Basic Percentage Formula
Percentage = (Part / Whole) × 100
Where:
- Part = The partial value you want to express as a percentage
- Whole = The total or reference value
Step-by-Step:
- 1
Identify the part and whole
Determine which number is the part and which is the whole.
- 2
Divide part by whole
This gives you the decimal fraction.
- 3
Multiply by 100
Convert the decimal to a percentage.
Worked Examples:
What percentage is 45 of 200?
Part: 45Whole: 200
Result: 22.5%
(45 / 200) × 100 = 22.5%
Percentage change
Old value: 80New value: 100
Result: 25% increase
((100 - 80) / 80) × 100 = 25%